generally,with automatic climate control,the fan may shut down,but it keeps the compressor constitently engaged,this is so you will have a burst of ice cold air.it does make the fan go up and down in speed,but the compressor has to remane constantly engaged,if you dont like this you should run it manually and remove it from the auto selection.it will save you some gas,but it willtake longer to kool,being thats the compressor has to restart to cool the air.